Ms. AF was a 54-year-old woman who came to see me with complaints of electric shock-like pain in her leg after a leg fracture she suffered during a fall. My physical examination and different types of tests I ordered convinced me that the cause of her pain (after the fracture healed), was a damaged nerve at the site of her ankle. Injury to nerves after some kind of trauma (a fracture or damage of muscles and ligaments) occurs infrequently, but when it does, it’s a very difficult, usually life-long problem. Besides her pain, her worst problem was immense fatigue and daytime sleepiness. She said she “could not keep her eyes open” during the day.
She could fall asleep watching TV, reading a book or even talking to someone. She was afraid to drive as she felt drowsy behind the wheel. It was not hard to figure out the problem. It was her neuropathic leg pain that was interrupting her sleep. While she would go to bed early, she would have hard time falling asleep and even harder time remaining asleep. So, she would be up hour after hour rubbing the leg, taking pain medications and watching TV to “forget the pain”. Exhaustion would finally get the best of her and she would collapse in bed for a couple of hours then be up again in the morning, feeling as tired as she was before she went to bed. She had accumulated a huge “sleep deficit” over the many months of her affliction. After a couple of weeks of bad sleep, she would “crash” and sleep the “sleep of death” as she put it for nearly 18 hours. She would subsequently repeat this pattern – again and again.
Sleep is a natural state that recurs regularly, and it is necessary for survival, with the person (or animal) in a state of partial or total unconsciousness. In sleep sensory stimuli are blocked and activity of muscles is suspended. Sleep helps conserve energy by decreasing metabolism by 5–10%. During sleep numerous functions are accomplished such as memory consolidation (making permanent what was learnt in the awake state), while it enhances growth and rejuvenates the immune, nervous, skeletal and muscular systems. All mammals (breast feeding animals), all birds, and many reptiles, amphibians, and fish need ssleep. When we are awake the brain “oscillates” with fast waves called alpha, and is fully active. These “oscillations” are picked up during an electroencephalogram (EEG) during which electrodes are attached at specific points on the surface of the skull.
Sleep is divided into two broad categories: rapid eye movement (REM) and non-rapid eye movement (NREM or non-REM) sleep. The American Academy of Sleep Medicine further divides NREM into three stages: N1, N2, and N3.
NREM stage 1: The sleep is light as this is a stage between sleep and wakefulness (light sleep). The person becomes drowsy. The brain oscillates with slow waves (4-7 Hz or cycles per second) and the muscles are active. At this stage stimuli of low intensity can wake up the person.
NREM stage 2: In this stage of deeper sleep, it is harder to awaken the sleeper. Conscious awareness of the environment is gone, activity of the muscles decreases and faster waves (theta waves 12-15 Hz or c/sec) appear.
NREM stage 3: This is truly the stage of deep sleep. The body’s metabolism slows down, and sleep is dominated by very slow waves called delta (0.5-4 Hz or c/sec). It promotes immune function and secretion of growth hormone. Many environmental stimuli fail to produce any reactions.
REM: Rapid eye movement sleep is also paradoxical sleep because although the sleeper shows fast EEG waves similar to a waking state, most muscles are “paralyzed” and it is harder to wake up than at any other sleep stage. Most dreams we can remember occur at this stage. Brain activity is very high with brain oxygen consumption even greater than when the sleeper is awake. This stage of sleep is necessary for consolidation of memory (what we have learnt in our awake stage), and for regulation of mood (the way one feels). REM sleep accounts for 20-25% of total sleep, and occurs approximately every 90 minutes.
Pain by itself can disrupt our sleep, as it activates certain areas of the brain that are responsible for our awake state and dampens areas responsible for initiation and maintenance of sleep. It may impair healing leading directly to further pain, it affects the areas central nervous system areas responsible for the way we cope with pain experiences, and “consumes” mental energy that is normally devoted to attention and concentration.
Research has shown that patients with unremitting pain are as impaired while driving as someone with a blood alcohol concentration level of 0.08% (Veldhuijzen et al, Pain, 2006;122:28-35). Ms. AF was unable to reach the deep stage of sleep, which is restorative and in general what we call her “sleep architecture” was severely disturbed.
So, how did I address Ms. AF’s neuropathic leg pain? She was already taking strong painkillers to no avail, but what I added was a particular drug that works on “injured nerves” by dampening the abnormal firing that caused the electric shock-like pains to her leg (pregabalin). This same drug has been shown to have a specific effect on sleep as well. So, with one shot I was aiming to kill the proverbial “two birds with one stone”. I was right. When Ms. AF came to see me 2 months later, she was a happier person and looked very refreshed. Her pain had improved considerably and so did her sleep – she experienced fewer awakenings, much less fatigue, reduced daytime sleepiness and her quality of life had greatly improved.
Next time you or a loved one suffers from unremitting pain and sleep problems, bring this to the attention of your doctor. Addressing pain first may indeed improve the quality of your sleep.
Angela Mailis Gagnon, MD, MSc, FRCPC(PhysMed)
Director, Comprehensive Pain Program,
Senior Investigator, Krembil Neuroscience Centre
Toronto Western Hospital,
Chair ACTION Ontario